This article covers using a single MetaMask wallet in multiple locations. If you want to read about using multiple wallets, see here.
One of the benefits of using MetaMask is that you can use your Secret Recovery Phrase to access your wallet on multiple computers or smartphones. You're not bound permanently to any single device.
To access your wallet on a new device, use your Secret Recovery Phrase to restore your wallet.
Though your Secret Recovery Phrase will give you access from any device, you'll need to set up a password again, and re-add any networks or tokens that you need. This is because this data is saved locally in each instance of MetaMask.
If you have more than one address (account) associated with your Secret Recovery Phrase — i.e. you used the 'Create account' button at some point — they will be restored automatically if they have a non-zero balance of ETH. Otherwise, you can just add them back by hitting 'Create account' again until you have all the ones you need. Read more here.